Cause
Incomplete particulate filter regeneration
A regeneration that started and did not finish, leaving the filter loaded and the module's count of failed attempts rising. One incomplete regeneration is not a fault — the process needs sustained load and takes fifteen minutes or more, and a journey that ends first will interrupt it. A pattern of them is the fault, and the count is the number to read.
Interruption has two quite different causes and they need separating. The journey ended, which is usage; or the module aborted because a condition went out of range — exhaust temperature not reached, a sensor disagreeing, fuel level too low, or another fault inhibiting the process. The stored abort reason is what distinguishes them, and it is far more useful than the code itself.
The consequence compounds. Each incomplete attempt leaves the load higher, and a higher load makes the next regeneration hotter and more likely to be aborted for over-temperature — so the system walks itself into a filter that can no longer regenerate on the road. Read the soot load and the failed-attempt count together before deciding between a forced regeneration, a repair, or a conversation about how the vehicle is used.
Typically a moderate job.
Some of these codes mean you should stop driving
2 of the 6 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (6)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2002 Particulate Filter Efficiency Below Threshold — Bank 1 Likely for this code High
- P2003 Particulate Filter Efficiency Below Threshold — Bank 2 Likely for this code High
- P2428 Exhaust Gas Temperature Too High Bank 1 Likely for this code Stop driving High
- P2429 Exhaust Gas Temperature Too High Bank 2 Likely for this code Stop driving High
- P24A2 Particulate Filter Regeneration Incomplete Bank 1 Likely for this code Moderate
- P24A4 Particulate Filter Restriction - Soot Accumulation Too High Bank 1 Likely for this code High
Information, not instruction
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